1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a printing apparatus for a liquid crystal display (LCD) device and a patterning method using the same.
2. Discussion of the Related Art
Among various ultra-thin flat type display devices, which include a display screen having a thickness of no more than several centimeters, liquid crystal display (LCD) devices are widely used for notebook computers, monitors, aircraft, etc. because they have advantages such as low power consumption and portability.
An LCD device includes lower and upper substrates facing each other with a predetermined interval therebetween and a liquid crystal layer formed between the lower and upper substrates.
The lower substrate includes a gate line, a data line, and a thin film transistor. The gate line is formed perpendicular to the data line to define a unit pixel region. The thin film transistor is formed adjacent to a crossing of the gate and data lines and serves as a switching device. In addition, a pixel electrode is connected to the thin film transistor.
The upper substrate includes a black matrix layer for shielding the gate line, the data line and the thin film transistor from light, a color filter layer formed on the black matrix layer, and a common electrode formed on the color filter layer.
The above LCD device includes various elements formed by repeated steps. Photolithography may be used to form the elements in various shapes.
A patterning method using a photolithographic process of the related art will be described with reference to the accompanying drawings.
FIGS. 1A to 1C are cross sectional views illustrating a patterning process of the related art using photolithography.
As shown in FIG. 1A, a pattern material layer 20 is formed on a substrate 10, and a photoresist layer 21 is formed on the pattern material layer 20.
As shown in FIG. 1B, a mask 25 with a predetermined pattern is positioned above the photoresist layer 21, and then light is provided to the substrate 10 by an exposure apparatus.
As shown in FIG. 1C, the photoresist layer 21 is patterned by a development process. The pattern material layer 20 is etched using the patterned photoresist layer 21 as a mask to obtain a desired pattern 20a. 
The above photolithographic process uses the photoresist layer and the mask having a predetermined pattern that increases the manufacturing cost. In addition, photolithography requires exposure and development, which are complicated processes that increase manufacturing time.
To overcome these problems associated with photolithography, new patterning methods have been developed, such as a printing method using a printing roller.
A patterning method using a printing roller according to the related art will be described with reference to the FIGS. 2A to 2D.
FIGS. 2A to 2D are cross sectional views illustrating a process for forming a pattern material layer on a substrate using a printing roller according to the related art.
As shown in FIG. 2A, a printing roller 30 having a blanket 32 adhered thereonto is prepared. Then, a pattern material 20 is coated on a surface of the printing roller 30 by a printing nozzle 40.
As shown in FIG. 2B, the printing roller 30 having the blanket 32 adhered thereonto rolls on a printing plate 50 having a plurality of projections 55. Accordingly, some pattern material 20b is printed on the projections 55 of the printing plate 50, while other pattern material 20a remains on the printing roller 30. That is, a predetermined pattern of the pattern material is formed of pattern material 20a remaining on the printing roller 30.
The blanket 32 adhered to the surface of the printing roller 30 is formed of a resin material having a predetermined elasticity. The elasticity of the blanket 32 decreases friction between the printing roller 30 and the printing plate 50 when printing the pattern material 20 of the printing roller 30 onto the printing plate 50.
As shown in FIG. 2C, as the printing roller 30 having the pattern material of the predetermined pattern rolls on a substrate 10, the pattern material 20a is printed onto the substrate 10.
The patterning method using the printing roller and the printing plate does not use a mask having the predetermined pattern and does not use exposure and development processes, thereby decreasing the manufacturing cost and time.
However, the patterning method using the printing roller according to the related art has the following disadvantages.
In the patterning method using the printing roller according to the related art, the pattern material is directly coated on the printing roller having the blanket by the printing nozzle. Solvent included in the pattern material may be absorbed into the blanket causing the blanket to deform or swell.